In the use model that dominates the Internet today, communication equipment (1) that produces data streams is situated at the ends or edges of the network. The data are sent from the source endpoint to the destination endpoint using the network system. The network system comprises local networks on the source and destination side (13), one or more local Internet Service Providers (ISP, 10) and one or more transport networks (11) as shown in FIG. 1.
Local networks (13) implement secure communication environments typically with private addresses and a firewall toward the rest of the Internet. Local Internet service provider networks (10) aggregate a number of local networks and use the transport providers (11) to reach each other.
Data packets enter the network from the end systems typically using a socket interface. In this model, the socket is identified by the pentuple of (source address, destination address, source port number, destination port number, protocol type). The packets comprise two parts: a header and a payload. The header provides control information, while the payload contains higher-layer (e.g., application-level) data. The header identifies said pentuple.
The data are forwarded between the forwarding devices (20) hop-by-hop using the information in the packet header. Although additional functionality can be implemented in a network, only this hop-by-hop forwarding toward the destination is implemented universally in the Internet.
Therefore, the network functionality an endpoint and its associated local network components typically implement is related to network addressing, including                a) Resolving of symbolic names to network addresses; and        b) Support for traversal of Network Address Translator (NAT) and firewall traversal.        
This simple interface does not allow the endpoint to select the end-to-end network path. Only the destination can be selected, and the network itself chooses the path. Typically, the packet will have to traverse multiple administrative authorities on its path.
The Internet provides so-called best-effort service to its users. This means the packets are transported from node to node toward their destination. They can be temporarily stored in the transit nodes awaiting available network capacity to continue the journey (buffering). The nodes are free to discard any packet; this would typically happen if a node receives more packets than it can forward in the moment and its buffering capacity is exceeded. No notification is given to the sender of the packet.
Many applications are interactive or bandwidth-demanding and have special network requirements such as low latency or low packet loss. These applications include among others gaming, business information feeds and multimedia communications. The traditional Internet model is insufficient for these applications. Advanced endpoint equipment may experience reduced quality due to congestion and packet loss.
Remedies that can improve the network quality and availability include establishing private wide area networks, both physical and virtual. Large enterprises may rent or deploy network capacity to connect their locations within the enterprise, but with a significant cost. Furthermore, one can influence the packet path using overlay or peer-to-peer architectures. Overlays and peer-to-peer networks cannot improve the network quality unless the network resources are provided to them with capacity guarantees, which is typically not the case.
Recently, some Internet Service Providers (ISPs) have extended their network access and Virtual Private Networks (VPN) services by offering new network service models.
One model is to provide the infrastructure for temporary data storage (caching) to enhance large-scale one-to-many data streaming. This model conserves bandwidth, but it assumes delay-tolerance and is not suitable for interactive, real-time communications.
Another network service model is to provide infrastructure with guaranteed bandwidth to customers with geographically diverse office locations together with associated private network maintenance services. This service is different from VPNs in that there can be given bandwidth and latency guarantees to the traffic, and the customer need not have maintenance personnel employed. The model is however limited to the locations where the provider has physical infrastructure available, and cannot be extended to arbitrary communication peers.
Some providers build their business model on extensive Border Gateway Protocol (BGP) peering with locally present ISPs, enhancing the performance of their hosting services. This method improves the network service quality only locally.
Finally, some providers rent network capacity or deploy it themselves where needed and provide end-to-end guaranteed bandwidth service. This approach provides excellent network infrastructure, but is coarse and expensive and therefore reserved only to the most well-funded enterprise customers. Communication with arbitrary peers is not possible.